Manufacture of zinc oxide



Patented Feb. 23, 1926.

sisu FFI.

HOWARD H. UTLEY AND JEAN MCCALLUM, OF FLORENCE, COLORADO, ASSIGNORS TO RIVER SMELTING AND REFINING COMPANY, OFST. LOUIS, MISSOURI, A CORPORA- TION OF MAINE.

MANUFACTURE OF ZINC OXIDE.

No Drawing.

To all whom it may concern:

Be it known that we, HOWARD H. UTLEY, a citizen of the "United States, and a resident of the city of Florence, in the county of Fremont and State of Colorado, and JEAN MoCALLUM, a citizen of the United States, and a resident ofthe city of Florence, in the county of Fremont and State of Colorado, have invented a new and useful Improvement in Manufacture of Zinc Oxide, of which the following is a specification.

Our invention relates to. the removal of lead and impurities from an igneous concentrate or fume product and has for its principal object to devise a process suitable for the manufacture of commercial zinc oxide from igneous zinc concentrates or zinc fume product or other similar material containing lead and impurities. It consists principally in chloridizing the lead and other impurities of the said materials in order to remove the lead and other impurities and then reducing the zinc and burning it to an oxide. It also consists in other features hereinafter described and claimed. Heretofore it has been uneconomical to manufacture the so-called lead-free and low leaded grades of commercial zinc oxide from ores containing any considerable percentage oflead; and it has been the practice commercially to select zinc ores substantially free from lead for the manufacture of the so-called lead-free zinc oxide. Wehave found that by proper treatment, zinc ores and zinc concentrates containing lead and other impurities may be utilized for this purpose and that a commercially lead-free zinc oxide superior in all respects to the commercial products now on the market may be economically manufactured from such ores and concentrates.

We prefer to start withthe fire process concentrates nown as'zinc concentrates, which consist mainly of a mixture of zinc oxide and lead sulphate together with some zinc sulphate and some lead oxides and other impurities. These so-c'alled zinc concentrates are a finely -pulverulent bag house product resulting from the smelting of sulphide ores as, for instance, by the process set forth in Hall Patent No. 1,276,058, dated August 20, 19 18.

With the zinc concentrate is mixed com- Application filed June 7,

of mixed ores commonly 1923. Serial N0. 644,054.

mon salt (sodium chlorid or other suitable chlorides) in suflicient quantity for chloridizing the lead and other impurities. The mixture is then heated to a temperature in the neighborhood of 800 to 1000 centigrade more or less for about two hours more or less. Under these circumstances, the lead and other impurities unite with the chlorin,

of the salt to form lead and other chlorides, and the sodium of the salt combines with sulphur of the charge to form sulphate of The residue remaining after the removal:

of lead and other impurities from the charge is a granular pro uct consisting of zinc oxide, sulphate of sodium and minor impurities; and'thenext ste in the process is to effect the separation o the; zinc and its recovery in the form of zinc oxide. For

this purpose, said residue is mixed with asuitable reducing agent, such as coke breeze or granulated coke or anthracite dust or charcoal chips, and the mixture is then shoveled or otherwise suitably fed into a heated Wetherill grate or other suitable.

furnace. Under theseiconditions, the zinc oxide is reduced to metallic form and the zinc is immediately burnt to an oxide which passs out in the form of a fume. This fum 'is collected in the bag house in the usual manner and constitutes an exception ally pure zinc oxide in themost desirable form for ordinary commercial purposes, es-

' pecially for use in paint making and for use in the. manufacture of rubber goods. The process is adapted to produce zinc oxides containing any desired percentage of lead, as well as to produce lead free zinc oxide, as above described. By-varying the amount of salt or other chlorid used and by varying the length of time that the process 1s carried on, a zinc oxide containing any' desired duced.

Under some circumstances it may be preferable to leach or wash the residue remaining after the chloridizing operation, in orpercentage of lead may be pro- I w ereas wet processes have heretofore been re uired for th1s purpose.

invention are der to remove sodium sulphate and sodium chloride therefrom. The leaching or wash mg erl and giveaveryhigh recovery of zinc.- ong the rinci al advantages of our rst, the fact. that it enables mixed ores to be used for the production of a commercially pure and high grade product'in place of the more limited lead-free ores that have heretofore been required,

' and second, it provides a feasible method of so arating zinc from lead by a dry process ile we have described our processes applied to the treatment of zinc concentrates, it is obviously applicable to the treatmentof other zinc and lead mixtures.

For instance, it is especially a plicable to the so-called leaded zinc oxide w ich is a commercial zinc oxide containing lead. It is also, eciallyap licable to b roducts produced in the mam ifacture of Zirib oxide from lead bearing ores or concentrates. What we claim is: H 1. The rocess of manufacturing zinc oxide from ume product containing zinc and lead, which comprises chloridizing'the-lead' and other chloridizable matter and thereby separating by volatilization the lead and other chloridlzable matter from the zinc oxide, mixing the residue with carbonaceous reducing material and, roasting the mixture.

2. The process of manufacturing zinc oxide, which comprises chloridizing by heat fumelcontaining zinc and lead to remove the I fume bearing material, which consists of impure zinc oxide lead sulphate and other impurities or sulphates, such process consisting of chloridizing this fume, with proper amount of chloridizing agent to remove lead and other impurities and subsequently roasting the residue in presence of carboproduces a product that will burn propto volatilize said zinc and then convert it back into zinc oxide, removing said zinc oxide and cooling and collecting it in. finely divided owder.

5. T e rocess of manufacturing zinc oxide from ume product containing zinc and lead, which comprises chloridizing the lead and other chloridizable matter, at a temperature sufiicient to volatilize and remove the lead and other volatile chlorids produced thereby, leaching or washing the residue, then mixing the residue with carbonaceous reducing material and roasting the mixture.

6. The process of manufacturin zinc oxide which comprises chloridizing ume containing zinc and lead at a temperature sufiicient to volatilize and remove the lead and other volatile chlorids produced thereby, leaching the residue to remove any remaining chloridizing agent and other impurities -and then roasting the residue in the presence' of a carbonaceous reducing agent.

' 7. The process of manufacturing zinc oxide from a mixed charge of zinc and lead fume bearing material, which consists of impure zinc oxide, lead sulphate and other impurities or sulphates, suchprocess consisting of chloridizing this fume in the presence of a chloridizing agent to volatilize and remove lead and other impurities, leaching the.

residue to remove any remaining chloridizing agent, sulphates or other impurities and subsequently roasting the residue in presence of carbonaceous material, on

duce zinc oxide. 1 I Signed at Florence, Colorado, this 31st day of May, 1923. 5

' HOWARD H, UTLEY. JEAN MGCALLUM.

grates to pro 

